If it happens in a place that makes a difference - and it does sometimes! - don't rip out the entire seam. Just the few stitches that turned the seam allowance the wrong way. It only takes a second or two. I want those seams out of my way when I hand quilt so I do it. I also finally purchased some Clover fork pins. They are quite expensive and I don't use them a lot, but they keep things going in the right direction like nothing else!